Nonlinear Processes in Geophysics www.nonlin-processes-geophys.net 1023-5809 1607-7946 17 3 2010 10.5194/npg-17-287-2010 http://www.nonlin-processes-geophys.net/17/287/2010/ http://www.nonlin-processes-geophys.net/17/287/2010/npg-17-287-2010.html http://www.nonlin-processes-geophys.net/17/287/2010/npg-17-287-2010.pdf 287 292 2010-06-16 Is current disruption associated with an inverse cascade? Z. Vörös zoltan.voeroes@uibk.ac.at A. Runov M. P. Leubner W. Baumjohann M. Volwerk Institute of Astro- and Particle Physics, University of Innsbruck, Innsbruck, Austria UCLA, Los Angeles, USA Space Research Institute, Austrian Academy of Sciences, Graz, Austria Current disruption (CD) and the related kinetic instabilities in the near-Earth magnetosphere represent physical mechanisms which can trigger multi-scale substorm activity including global reorganizations of the magnetosphere. Lui et al. (2008) proposed a CD scenario in which the kinetic scale linear modes grow and reach the typical dipolarization scales through an inverse cascade. The experimental verification of the inverse nonlinear cascade is based on wavelet analysis. In this paper the Hilbert-Huang transform is used which is suitable for nonlinear systems and allows to reconstruct the time-frequency representation of empirical decomposed modes in an adaptive manner. It was found that, in the Lui et al. (2008) event, the modes evolve globally from high-frequencies to low-frequencies. However, there are also local frequency evolution trends oriented towards high-frequencies, indicating that the underlying processes involve multi-scale physics and non-stationary fluctuations for which the simple inverse cascade scenario is not correct. Alexakis A.: Nonlocal phenomenology for anisotropic magnetohydrodynamic turbulence, Astrophys. J., 667, L93–L96, 2007. Angelopoulos, V., McFadden, J. P., Larson, D., Carlson, Ch. 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